The release of a Brooklyn teenager who used a Facebook alibi to convince prosecutors he didn't commit a robbery may be a sign of things to come in criminal law, a cyberlaw expert said Thursday.

Evidence gleaned from social-networking sites previously has been used by prosecutors to disprove alibis or connect suspects to criminal activity, said Jonathan Ezor, a professor at Touro Law School in Central Islip.

Rodney Bradford, 19, was released from Rikers Island after 12 days behind bars when a Facebook message to his girlfriend showed he was at his father's Harlem apartment on Oct. 17 - not robbing two men in Brooklyn.

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Other people backed up Bradford's alibi, saying he was in Harlem on Oct. 17, according to published reports.

Prosecutors reportedly subpoenaed Facebook to verify Bradford sent the message from Harlem at the time the robbery took place.

Bradford could not be reached for comment Thursday. His attorney did not return calls for comment.

Ezor said the Facebook alibi may have created enough reasonable doubt to convince prosecutors to drop charges against Bradford. But it's not inconceivable for a sophisticated Internet user to falsify his or her whereabouts using social-networking sites, he said.

In theory, at least, a person could use a mobile device to create the appearance of working on a home computer - or simply ask a friend to use one's Facebook or Twitter address, Ezor said."There really is no way of proving who was at the computer, which is the problem with any Internet-based investigation," he said. "Today, one can update Facebook status or tweet Twitter from any device at any location."